JP3241047B2 - Improved electrochemical hydrogen storage alloy for nickel metal hydride batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Continuing Information The present invention is a continuation-in-part of US patent application Ser. No. 08 / 136,066, filed Oct. 14, 1993. US Patent 08/1
No. 36,066 is a continuation-in-part of U.S. Pat. No. 5,277,999 (filed on Aug. 25, 1992 as U.S. Patent Application No. 07 / 934,976). U.S. Pat.No. 5,277,999 is U.S. Pat.
No. 56 (filed Aug. 14, 1991 as U.S. Patent Application No. 07 / 746,015). US Patent 5,238,75
No. 6 is a continuation-in-part of U.S. Patent No. 5,104,617 (filed August 26, 1990 as U.S. Patent Application No. 07 / 515,020).

TECHNICAL FIELD OF THE INVENTION The present invention relates to electrochemical hydrogen storage alloys and rechargeable electrochemical cells using these alloys. More particularly, the present invention relates to rechargeable batteries and batteries having a cathode formed from a multi-component electrochemical hydrogen storage alloy. Batteries incorporating these alloys have significantly improved performance characteristics such as energy density, charge retention, cycle life and low temperature performance as compared to known rechargeable batteries using hydrogen storage alloys. The present invention also describes a unique alloy utilizing a significantly reduced amount of Co without loss of performance.

Background of the Invention Rechargeable batteries utilizing a nickel hydroxide anode and a metal hydride forming cathode ("metal hydride batteries") are known in the art. When an electrical potential is applied between the electrolyte in the metal hydride battery and the metal hydride electrode, the cathode material (M) is charged by electrochemical absorption of hydrogen and electrochemical generation of hydroxyl ions as follows. ; during discharge is released stored hydrogen to form water molecules, generating _{electrons: M + H 2 O + e} - <-> M-H + OH - ( where a processing proceeds to the right reaction charge, left The reaction that proceeds to is discharge).

The reactions that take place at the anode of a nickel metal hydride battery are also reversible. Most metal hydride batteries use a nickel hydroxide anode. The following charge and discharge reactions occur in nickel hydroxide positive _{electrode: Ni (OH 2) + OH} - <-> NiOOH + H 2 O + e - ( where a processing proceeds to the right reaction discharge, and charging the reaction to proceed to the left) .

In metal hydride cells having a nickel hydroxide anode and a hydrogen storage cathode, the electrodes are typically separated by a nonwoven felted nylon or polypropylene separator. The electrolyte is typically, for example, 20-45% by weight potassium hydroxide.

The first hydrogen storage alloys that have been examined as a battery electrode material was TiNi and LaNi _5. Many years have been spent on these studies, as these simple binary intermetallics were known to have adequate hydrogen bond strengths for use in electrochemical applications. However, despite extensive efforts, researchers have found that these intermetallics are very unstable and have many harmful effects such as slow discharge, oxidation, corrosion, poor rate, and poor catalysis. Found that the electrochemical value was inadequate due to the different effects. These simple alloys for battery use have been developed by battery developers with NiC
d reflects the tendency to traditionally utilize single element pairs of crystalline materials such as NaS, LiMS, ZnBr, NiFe, NiZn and Pb-acids. To improve the electrochemical properties of binary intermetallics while retaining hydrogen storage efficiency, early researchers
We started to improve TiNi and LaNi ₅ system.

Improvements to TiNi and LaNi ₅ were made by Stanford R. of Energy Conversion Devices (ECD) in Troy, Michigan, USA.
Started by Ovshinsky. Ovshinsky and his team at the ECD have shown that trust in simple, relatively pure compounds is a major drawback of the prior art. Previous studies have found that catalysis relies on surface reactions at irregular sites in the crystal structure. Relatively pure compounds were found to have a relatively low density of hydrogen storage sites, and the types of sites available occurred by accident and were not designed into the body of the material. Thus, it has been discovered that the efficiency of hydrogen storage and subsequent release of hydrogen is substantially less than would be obtained if more diverse active sites were available.

Ovshinsky has already discovered that the number of surface sites can be significantly increased by making an amorphous film that resembles the surface of the desired relatively pure material. Ov
shinsky is Principles and Applications of Amorphici
ty, Structural Change, and Optical Information Encod
ing, 42 Journal De Physique at C4-1096 (August 1981
"Amorphousness is a general term that refers to the lack of evidence from a wide range of periodic X-ray analyses, and does not fully describe the material. To understand amorphous materials, several factors must be considered: the types of chemical bonds, the number of bonds created by local order (ie, their coordination), and the resulting chemical configurations for the various configurations. And factors such as the influence of the geometric total local environment, etc. Amorphousness is not determined by random packing of atoms that are considered hard spheres, and amorphous solids are simply randomly embedded. Amorphous materials are those in which the electron configuration is caused by free-energy forces, and they are the interaction matrices that can be specifically defined by the chemistry and coordination of the constituent atoms. It should be considered to be made from Rix, using multi-orbital elements and a variety of preparation techniques to handle the normal relaxation reflecting the equilibrium conditions, and the three-dimensional freedom of amorphous materials, A new kind of amorphous material (chemically modified material) can be made ... "Once the amorphous state is understood as a means to introduce surface parts to the film, it can be applied not only to amorphous materials but also to crystalline materials. "Irregular" (porosity, topology, crystallites,
It is now possible to make planned "irregularities" that take into account the local features of the region and the local order effects, such as the distance between the regions. Thus, rather than seeking a material modification that creates a maximum number of ordered materials with accidentally generated surface irregularities, Ovshinsky's team at ECD says that the `` irregularities '' where the desired irregularities can be made to order. I started making the ingredients. See U.S. Patent No. 4,623,597, which is incorporated herein by reference.

The term "irregular" as used herein corresponds to the meaning of the term used in the document, for example: "A disordered semiconductor can exist in several structural states This structural factor constitutes a new variable in which the physical properties of the [material] ... can be adjusted, and structural irregularities are a new composition in the metastable state that far exceeds the limits of thermodynamic equilibrium. And the possibilities of preparing mixtures are expanding, so we would like to further distinguish the following features: many irregular [materials] ... within a narrow range of parameters that can be adjusted Dramatic changes in the physical properties of these materials can be achieved, e.g. by giving the elements new coordination numbers, etc. "
(SROvshinsky, The Shape of Disorder, 32 Journal o
f Non-Crystalline Solids at 22 (1979) (emphasis added later).

The "narrow range order" of these irregular materials is Ovshinsk
y (The Chemical Basis of Amorphicity: Structure and
Function, 26: 8-9 Rev. Roum.Phys.at 893-903 (198
This is explained in more detail by 1)) as follows: "Narrow range order is not preserved ... In fact, if the crystal symmetry is broken, it is impossible to maintain the same narrow order. Because the order of the narrow range is regulated by the force field of the electron orbit, the environment is fundamentally different between the corresponding crystalline and amorphous solids, in other words, the electrical and chemical properties of the material. It is the interaction of local chemical bonds with their surrounding environment that determines the physical and physical properties, and these in amorphous materials cannot be the same as in crystalline materials ... Orbital relationships that can exist in three dimensions in materials that are regular but not crystalline are the basis for new geometric properties,
Many are intrinsically anti-crystalline in nature. Bond strains and atomic displacements may be sufficient reasons to cause amorphousness in single component materials. However, to fully understand its amorphousness, one must understand the three-dimensional relationships inherent in the amorphous state. Because the three-dimensional relevance forms an internal topology that is incompatible with the translational symmetry of the crystal lattice ... what matters in the amorphous state is the infinite number of materials that have no crystalline counterpart. Can be made, and even those with it are primarily similar in chemical composition. The spatial and energy relationships of these atoms are quite different between amorphous and crystalline forms, but their chemical elements can be the same ... "Narrow range (or local) order is incorporated herein by reference." Compositionally Varied Materials and M
Ovsh entitled "ethod for Synthesizing the Material"
This is detailed in insky U.S. Pat. No. 4,520,039. This patent describes how irregular materials do not require periodic local order and, using Ovshinsky's technology, the high accuracy and control of local placement so that new phenomena can be made quantitatively Discuss how spatial and orientational arrangements of similar or dissimilar atoms or groups of atoms are possible. Furthermore, the patent states that the atoms used are "d-band" or "f-band"
The regulatory aspects of interaction with the local environment are not limited to the physical properties (and thus function) of the material
It is argued that any atom that plays a prominent role physically, electrically or chemically so as to affect the These techniques provide a means to synthesize new materials that are simultaneously irregular in several different senses.

By forming hydride metal alloys from such random materials, Ovshinsky and his team could greatly enhance the reversible hydrogen storage properties required for efficient and economical battery utilization, High density energy storage,
Batteries can be made with efficient reversibility, high electrical efficiency, body hydrogen storage without structural changes or loss of capacity, long cycle life and high discharge capacity.

The enhanced characteristics of these alloys derive from tailoring the local chemical order and thus the local structural order by introducing selected modifier elements into the host matrix. Obtained from Disordered hydrides have a substantially increased density of catalytically active sites and storage sites as compared to simple, ordered crystalline materials. These additional sites contribute to improved efficiency of electrochemical charging / discharging and increased electrochemical energy storage capacity. The nature and number of storage sites can even be designed independently of the catalytically active sites. More specifically, these alloys are tailored to allow for the main storage of dissociated hydrogen atoms with a binding force within a reversible range suitable for use in second battery applications.

Based on the pioneering principles described above, some of the most efficient electrochemical hydrogen storage materials have been formulated. These include modified La
Active materials based on Ni ₅ and TiVZrNi can be mentioned. Ti−
Active materials based on the V-Zr-Ni system are disclosed in U.S. Pat. No. 4,551,400 ("the '400 patent"), which is incorporated herein by reference. These materials form hydrides reversibly to store hydrogen. All materials used in the '400 patent generally have a Ti-V-Ni composition (where at least T
i, V and Ni have at least one kind of Cr, Zr and A
l). '400 patent materials are multiphase materials, which comprises one or more TiVZrNi type phases with a crystal structure of the C ₁₄ and C ₁₅ type, but is not limited thereto. The following formula is specifically disclosed in the '400 patent: (TiV _2-x Ni _x ) _1-y M _y (where x is between 0.2 and 1.0; y is between 0.0 and 0.2 And M = Al or Zr), Ti _2-x Zr _x V _4-y Ni _y (where Zr is partially substituted for Ti; x is 0.0
Lies between 1.5 when; and y is 0.6 to be between 3.5); and _{Ti 1-x Cr x V 2} -y Ni y ( where, Cr is partially substituted for Ti; x is 0.0
And between 0.75; and y is between 0.2 and 1.0. ) Other Ti-V-Zr-Ni alloys may be used for rechargeable hydrogen storage cathodes. One such family of materials is Venkatesan, Reic, incorporated herein by reference.
U.S. Pat. No. 4,728,586 to Hman and Fetcenko ("'58
6 patents)) (Enhanced Charge Retention Electrochemic
al Hydrogen Storage Alloys and an Enhanced Charge
Retention Electrochemical Cell). The '586 patent covers Ti, V, Zr, Ni and the fifth component Cr.
A specific subclass of these Ti-V-Ni-Zr alloys consisting of

In a particularly preferred example of the '586 patent, the alloy has the following _{composition: (Ti 2-x Zr x} V 4-y Ni y) , where _1-z Cr _z, x is from 0.00 to 1.5, y is 0.6 to 3.5
And z is an effective amount of less than 0.20. These alloys are stoichiometrically 80 atomic% V-Ti-Zr-Ni
Part and up to 20 at.% Cr (where (Ni +
The ratio of (Ti + Zr + Cr + optional modifier) to (V + optional modifier) may be between 0.40 and 0.67). The '586 patent shows the potential for additives and modifiers beyond the Ti, V, Zr, Ni and Cr components of the alloy, specific additives and modifiers, the amount and interaction of these modifiers , And the particular advantages that can be expected from them.

The V-Ti-Zr-Ni series described in the '586 patent has an intrinsically higher discharge rate capability than previously described alloys. This is a result of the substantially higher surface area at the metal / electrolyte interface for electrodes made from V-Ti-Zr-Ni materials. The surface roughness factor (total surface area divided by geometric surface area) of the V-Ti-Zr-Ni alloy is about 10,000. This value represents a very high surface area and is supported by the intrinsically high capacity of these materials.

The characteristic surface roughness of the metal / electrolyte interface is a result of the irregular nature of the material. Since all constituent elements, as well as many alloys and their phases, are present throughout the metal, they are also manifested by cracks that form at the surface and at the metal / electrolyte interface. Thus, the characteristic surface roughness describes the interaction of the physical and chemical properties of the host metal and alloy in an alkaline environment and the crystallographic phase of the alloy. These microscopic, chemical, physical and crystallographic parameters of the individual phases within the hydrogen storage alloy material appear to be important in determining its macroscopic electrochemical properties.

In addition to the physical properties of the roughened surface, V-Ti-Zr-
Ni alloys tend to achieve steady state surface composition and particle size. This phenomenon is described in U.S. Pat. No. 4,716,088. This steady state surface composition is characterized by a relatively high concentration of metallic nickel. These observations are consistent with removal of titanium and zirconium from the surface at relatively high rates by precipitation of oxides and low rates of nickel solubilization, imparting porosity to the surface. The resulting surface appears to have a high concentration of nickel expected from the body composition of the hydrogen storage cathode. Nickel in the metallic state has conductivity and catalysis, and imparts these features to the surface. As a result, the surface of the hydrogen storage cathode is more catalytic and conductive than if the surface contained a high concentration of insulating oxide.

In contrast to the alloys based on the above Ti-V-Zr-Ni, modified LaNi ₅ type alloys are usually considered "ordered material" having different chemical and microstructure, Ti-V-Zr-Ni Shows different electrochemical properties compared to alloys. However, analysis has shown that while the early unmodified LaNi ₅ based alloys could have been ordered materials, more recently developed and highly modified LaNi ₅
Alloys show that this is not the case. Early rules LaNi
The performance of the _five alloys was inadequate. However, the currently used modified LaNi ₅ alloys had a high degree of modification (as the number and amount of elemental modifiers increased) and the performance of these alloys was significantly improved. This is due to irregularities imparted by the modifiers and their electrical and chemical properties. From a specific class of "rule" material, Ti-V
The development of modified LaNi ₅ type alloy to multiphase "disordered" alloys recent multicomponent currently very similar -zr-Ni alloys is shown in the following patents: (i) U.S. Pat. No. 3,874,928
US Patent No. 4,214,043; (iii) US Patent No.
4,107,395, (iv) U.S. Patent No. 4,107,405, (v) U.S. Patent No. 4,112,199, (vi) U.S. Patent No. 4,125,688,
(Vii) U.S. Pat. No. 4,214,043; (viii) U.S. Pat.
216,274, (ix) U.S. Patent No. 4,487,817, (x) U.S. Patent No. 4,605,603, (xii) U.S. Patent No. 4,696,873,
And (xiii) U.S. Pat. No. 4,699,856 (these references are discussed extensively in U.S. Pat. No. 5,096,667, which are specifically incorporated herein by reference).

Briefly described, in the reforming LaNi ₅ type alloy such as Ti-V-Zr-Ni based alloys, in accordance with modification degree is increased, the role of the early rule-based alloy, contributes to the special modifier And secondary importance compared to the nature and irregularities of the work. Furthermore, recent multi-component modified LaNi ₅ -based alloys show that these alloys have been modified according to established guidelines for TiVZrNi-based systems.
Highly modified modified LaNi ₅ type alloy and TiVrNi based alloy both in that it is disordered materials characterized by multiple-components and multiple phases are the same. Thus, there is no longer a significant difference between these two types of multi-component multi-phase alloys.

Prior art deficiencies Although prior art hydrogen storage alloys have introduced a variety of individual modifiers and combinations of modifiers to enhance their performance characteristics, the role of individual modifiers, There is no obvious teaching of the interaction with other alloy components or the effect of the modifier on particular operating parameters. Highly modified LaNi ₅ alloys had been analyzed for well-ordered crystalline materials, but in particular their effects were not clearly understood.

Prior art hydrogen storage alloys can generally provide improved performance attributes (eg, cycle life, discharge rate, discharge voltage, polarization, self-discharge, low temperature capacity and low temperature voltage). However, prior art alloys have resulted in cells that exhibit a quantitative improvement in one or two performance characteristics at the expense of a quantitative reduction in other performance characteristics. Often, the superior performance characteristics of these cells are only marginally better than the corresponding characteristics of other types of cells such as NiCd. Thus, all batteries made from the prior art were special purpose batteries whose performance characteristics represented a good or bad engineering compromise, and thus were closely tailored to the intended use of the battery. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a nickel-rich region in an oxide layer.

SUMMARY OF THE INVENTION One object of the present invention is a hydrogen storage alloy that exhibits improved capacity.

These and other objects of the present invention are satisfied by the following electrochemical hydrogen storage alloys and methods of forming the alloys: (base alloy) _a Co _b Mnc _c Fe _d Sn _e (where the base alloy is 0.1 to 60) Atomic% Ti, 0.1-40 atomic% Zr, 0-60 atomic% V, 0.1-57 atomic% Ni, and 0-56 atomic% Cr; b is 0-7.5 atomic%; c is 1
D is from 0 to 3.5 atomic%; e is from 0 to 1.5 atomic%; and a + b + c + d + e = 100 atomic%. ) Consisting of an irregular electrochemical hydrogen storage alloy.

An electrochemical hydrogen storage alloy with a Ni-rich alloy surface on the oxide surface.

Preparing (blending) an electrochemical hydrogen storage alloy containing components that are preferentially corroded during activation; and activating the alloy to create the Ni-rich region. For forming an electrochemical hydrogen storage alloy having an oxide on the oxide surface.

Compounding a first electrochemical hydrogen storage alloy; compounding a second alloy containing a component containing a component that is preferentially corroded during activation to leave a Ni-rich region; Electrochemically hydrogen storage having a Ni-rich alloy surface on an oxide surface, comprising: mechanically alloying a second alloy with the first alloy; and activating the mechanically alloyed first second alloy. The method of forming the alloy.

Following composition: at (Base _{Alloy) a Co b Mn c Fe d} Sn e ( here, base alloy 0.1 to 60 atomic% of Ti, 0.1 to 40 atomic% of Zr, 0 to 60 atomic% of V, 0.1 to Consists of 57 at% Ni and 0 to 56 at% Cr; b is 0 to 7.5 at%; c is 1
D is from 0 to 3.5 atomic%; e is from 0 to 1.5 atomic%; and a + b + c + d + e = 100 atomic%. An electrochemical hydrogen storage battery having a cathode composed of an irregular electrochemical alloy having

DETAILED DESCRIPTION OF THE INVENTION The disordered hydride metal alloy materials of the present invention are designed to have unique two-dimensional and three-dimensional electronic configurations by altering the three-dimensional interactions of the constituent atoms and their various orbitals. You. The irregularities of these alloys derive from compositional, positional and translational relationships, and are provided by the number, position and size of atomic crystals that are free to interact with normal crystal symmetry. From irregularities. This irregularity can have primitive properties in the form of compositional or positional irregularities provided over the body or over multiple areas of the material. These disordered alloys have a lower order than a highly ordered crystal structure that provides a single phase material as used in many prior art electrode alloys. The types of irregular structures that provide a local structural chemical environment for improved hydrogen storage properties according to the present invention include multi-component polycrystalline materials, microcrystalline materials, and amorphous materials having one or more phases that lack a wide range of compositional orders. , A multiphase material containing both amorphous and crystalline phases, or mixtures thereof.

The framework of the disordered metal hydride alloy is one or more host matrices. The host element is usually selected to be a hydride former and can be a lightweight element.
For example, the host matrix element can be based on LaNi or TiNi. The host matrix element is modified by introducing a selected modifier element which may or may not be a hydride former.

We believe that when multiple modifier elements (as described in the present invention) are introduced, independent of the original host matrix material, the result is excellent electrochemical properties. It has been found through enthusiastic analysis that it is an irregular material having The improvement in electrochemical properties is due to an increase in the number and range of catalytically active hydrogen storage sites. In particular,
Multi-orbital modifiers (eg, transition elements) provide a significantly increased number of storage sites due to the variety of bonding arrangements available. This leads to an increase in energy density. Modifications that result in a non-equilibrium material with a high level of disorder provide a unique bond configuration, orbital overlap (and thus range of bond sites). Due to different degrees of orbital overlap and irregular structure, slight structural rearrangements
Happens during a charge / discharge cycle or during a test,
Provides long cycle and shelf life.

The hydrogen storage properties and other electrochemical properties of the electrode materials of the present invention can be tunably varied depending on the type and amount of host matrix material and modifier elements selected to make the cathode material. . The cathode alloys of the present invention are resistant to degradation by poisoning due to the increased number of selectively designed storage sites and catalytically active sites that also contribute to long cycle life. Also, some of the sites designed in the material do not affect the active hydrogen sites,
Can combine with poisoning and withstand. The material thus formed has a very low self-discharge and thus has a good shelf life.

As discussed in U.S. Patent No. 4,716,088 (the disclosure of which is incorporated herein by reference), V-Ti-Zr-
The steady state surface composition of the Ni alloy can be characterized as having a relatively high concentration of metallic nickel. One feature of the present invention is a significant increase in the frequency of occurrence of these nickel regions as well as a more pronounced localization of these regions. More specifically, the material of the present invention has a nickel-rich region with a diameter of 50-70 ° distributed over the oxide interface, the distance between the regions being 2-300 ° depending on the location,
Preferably it is 50-100 °. This is illustrated in FIG. 1 where the nickel region 1 is located on the surface of the oxidized interface.
Shown as appearing as granules at 8,000 times. As a result of the increased frequency of these nickel regions, the materials of the present invention exhibit significantly increased catalysis and conductivity. The increased density of the Ni region in the present invention provides a powder particle having a Ni-rich surface. Prior to the present invention, Ni enrichment was unsuccessful in attempts to use microencapsulation. The method of Ni encapsulation results in the deposition of a layer about 100 mm thick at the metal-electrolyte interface. Such amounts are excessive and do not result in improved performance characteristics.

The Ni-rich region of the present invention can be made by two general methods of making.

1) The alloy having a surface area that is preferentially corroded during activation is specially prepared (blended) to create the Ni-rich area described herein. Without wishing to be bound by theory, for example, it is believed that Ni cooperates with elements such as Al in certain surface regions, and that these elements are preferentially corroded during activation, leaving the above-mentioned Ni-rich regions. Can be As used herein, "activation" is specifically applied to "etching," or electrode alloy powders, finished electrodes, or at any point in between to improve the hydrogen transfer rate, e.g., US Patent 4,71
No. 6,088 describes another method for removing excess oxide.

2) mechanically alloy the second alloy with the hydrogenated battery alloy, where the second alloy is preferentially corroded, leaving nickel-rich regions. An example of such a secondary alloy is NiAl.

Ovonic, TiVZrNi system, modified LaNi ₅ system, misch metal,
And LaNi ₅ alloy and pending U.S. patent application Ser.
Alloys having Ni-rich regions can be formulated for all known hydrogenated battery alloy systems, such as, but not limited to, the Mg alloys described in US Pat. No. 9,793.

More specific examples of hydride alloys that can be specially formulated as described in 1) and 2) above to create a Ni-rich region, or can be mechanically alloyed with a second alloy are as follows: alloy (here represented by the formula _{ZrMn w V x M y Ni z} , M is Fe or Co, w, x,
y and z are molar ratios of each element, where 0.4 ≦ w ≦
0.8, 0.1 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.2, 1.0 ≦ z ≦ 1.5, and 2.0 ≦ w + x + y + z ≦ 2.4). Any of the La or Ni components has an atomic ratio of greater than 0.1% and less than 25%, and is an Ia, II, II of the Periodic Table of Elements other than Lanthanides
I, substantially corresponding alloy to formula LaNi ₅ which is substituted by a metal M selected from IV and V a group. Formula TiV _2-x Ni
An alloy having _x (where x = 0.2-0.6). Formula T
i _a Zr _b Ni _c Cr _d M _x (where M is Al, Si, V, Mn, Fe, C
o, Cu, Nb, Ag or Pd, 0.1 ≦ a ≦ 1.4, 0.1 ≦ b
≦ 1.3, 0.25 ≦ c ≦ 1.95, 0.1 ≦ d ≦ 1.4, a + b + c +
d = 3 and 0 ≦ x ≦ 0.2. ). Formula ZrMo _d
An alloy having Mi _e, where d = 0.1-1.2 and e = 1.1-2.5. The formula Ti _1-x Zr _x Mn _2-yz Cr _y V _z (where 0.05 ≦ x ≦ 0.4, 0 ≦ y ≦ 1.0, and 0 ≦ z ≦ 0.4
It is. ). Wherein LNM ₅ (wherein, Ln is at least one lanthanide metal, M is at least one metal selected from the group consisting of Ni and Co.)
An alloy having At least one transition metal forming an alloy of 40-75% by weight selected from groups II, IV and V of the periodic table and at least one transition metal forming the balance of the alloy alloyed with the at least one transition metal An alloy comprising an additional metal, wherein the additional metal is selected from the group consisting of Ni, Cu, Ag, Fe, and Cr-Ni steel. An alloy consisting of the main structure of the Mm-Ni system; and a plurality of compound phases in which each component phase is separated in the main structure, wherein the volume of each compound phase is less than 10 μm ³ .

The most preferred alloy having a Ni-rich region is an alloy having the following composition: (base alloy) _a Co _b Mnc _c Fe _d Sn _e wherein the base alloy is 0.1 to 60 atomic% Ti, 0.1 to 0.1 atomic%. 40
Atomic% Zr, 0-60 atomic% V, 0.1-57 atomic% Ni,
And 0-56 at% Cr; b is 0-7.5 at%; c
Is 13-17 atomic%; d is 0-3.5 atomic%; e is 0-1.5 atomic%;
And a + b + c + d + e = 100 atomic%.

The creation of the Ni region of the present invention is consistent with the relatively high rate of removal from the surface by the deposition of titanium and zirconium oxides and the low rate of nickel solubilization, providing porosity to the surface. The resulting surface has a higher concentration of nickel than expected from the body composition of the hydrogen storage cathode. Nickel in a metallic state has electrical conductivity and catalytic action, and imparts these properties to the surface. As a result, the surface of the hydrogen storage cathode is more catalytic and conductive than if the surface contained a high concentration of insulating oxide.

One important consideration in formulating the alloys of the present invention relates to formulating specific alloys having an appropriate balance of corrosion and passivation properties to make a particular electrochemical alloy. According to the present invention, this process involves selecting a modifier from those shown in Table 1 below.

Usually, when added as a modifier, the elements listed in Table 1 make the following contributions to the final alloy mixture: i) Group I elements alter corrosion and storage and bonding properties; ii) Group II elements V, Ti, and Zr alter bond strength and corrosion; Cr, Al, Fe, and Sn alter corrosion, passivation, and catalytic phenomena; iii) All elements of group III are glass formers, Affects the formation of the lattice; and iv) Group IV Cu, Th, Si, Zn, Li, La and F affect the disorder and change the density of states.

The term "base alloy" as used herein is selected from the group consisting of amorphous, microcrystalline, polycrystalline, and combinations of these structures (as that term is described in U.S. Patent No. 4,551,400). Means a disordered alloy having a base alloy that is a disordered multi-component alloy having at least one structure. The terms “amorphous”, “crystallite”, and “polycrystalline” are used as defined in US Pat. No. 4,623,597, the disclosure of which is incorporated herein by reference. The alloy of the present invention is not limited to a particular structure. Preferably, the material of the present invention is classified as having a disordered structure, AB, TiVZrNi type, modified LaNi _5, LaNi _5, mischmetal, C _14, C _15, by a variety of other terms such Loeve phase Includes materials commonly mentioned.

More specific examples of base alloys are as follows:
Formula _{ZrMn w V x M y Ni z} ( wherein, M is Fe or Co, w,
x, y and z are molar ratios of each element, where 0.4 ≦
w ≦ 0.8, 0.1 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.2, 1.0 ≦ z ≦ 1.5,
And 2.0 ≦ w + x + y + z ≦ 2.4. An alloy represented by). One of the components of La or Ni is a metal M selected from Group Ia, II, III, IV and Va of the Periodic Table of Elements other than Lanthanides, with an atomic ratio of more than 0.1% and less than 25%. An alloy substantially corresponding to the formula LaNi ₅ replaced by Formula Ti _a Zr _b Ni _c Cr _d M _x (where M is Al, Si, V, M
n, Fe, Co, Cu, Nb, Ag or Pd, and 0.1 ≦ a ≦ 1.
4, 0.1 ≦ b ≦ 1.3, 0.25 ≦ c ≦ 1.95, 0.1 ≦ d ≦ 1.4, a
+ B + c + d = 3, and 0 ≦ x ≦ 0.2. ). The formula ZrMod _d Ni _e (where d = 0.1-1.2 and e = 1.1
~ 2.5. ). Formula Ti _1-x Zr _x Mn _2-yz Cr _y V
_z (where 0.05 ≦ x ≦ 0.4, 0 ≦ y ≦ 1.0, and 0 ≦
z ≦ 0.4. ). Equation LnM ₅ (where Ln
Is at least one lanthanide metal and M is at least one metal selected from the group consisting of Ni and Co. ). At least one transition metal forming an alloy of 40-75% by weight selected from groups II, IV and V of the periodic table, and at least one transition metal alloyed with the at least one transition metal to form the balance of the alloy; An alloy comprising an additional metal, wherein the additional metal is selected from the group consisting of Ni, Cu, Ag, Fe, and Cr-Ni steel. The main structure of the Mm-Ni system; and a plurality of compound phases in which each component phase is separated in the main structure (where the volume of each compound phase is 10 μm).
m ³ ).

The preferred composition of the base alloy according to the present invention is 0.1 to 6
0 wt% Ti, 0.1-40 atomic% Zr, 0-60 wt% V,
Contains 0.1-57 at% Ni and 0-56 at% Cr. The most preferred composition of the base alloy is 0.1-60% by weight Ti, 0.1-40% by atom Zr, 0.1-60% by weight V, 0.
It contains 1-57 at% Ni and 0-56 at% Cr.

In general, the alloys of the present invention have metal hydride battery cathodes that exhibit significantly higher storage capacity and other significant quantitative improvements in performance characteristics compared to prior art batteries. Surprisingly, most, if not all, embodiments of the present invention exhibit an improvement in their performance characteristics, and thus can be considered a universal application battery.

In accordance with the present invention, the preferred alloys of the present invention described above and in the Summary of the Invention can be further classified as having an irregular microstructure, wherein the hydrogen in a particular phase is either due to a low surface area or is limited. It is not easily released by oxides having porous or catalytic properties. Specific examples of the alloy of the present invention are shown in Table 2 below.

The effect of the addition of Mn can be seen in the cathode material of the present invention where the base alloy is modified with 12-17 atomic% Mn. In addition, the effect of Mn is modified when the base alloy is in any of the following combinations: (i) 6.5-7.5 atomic% Co, 13-17 atomic% Mn, and
0.2-2.5 at% Fe; (ii) 5.5-6.5 at% Co, 13.5-14.5 at% Mn, 1.
5-2.5 at% Al, and 0.25-1.0 at% Fe; (iii) 3.5-5.5 at% Co, 14.5-15.5 at% Mn,
0.5-2.5 at% Fe, and 0.2-1.0 at% Zn; (iv) 3.5-5 at% Co, 14.5-15.5 at% Mn, 0.5
~ 2.5 atomic% Fe, and 0.2-1.0 atomic% Sn.

Co has become one of the most widely used elements in rechargeable batteries. Due to its limited supply, Co has also become more expensive to use. Recently, the price of Co has increased by 5%. The price of Co is 2000
By the year it is expected to increase by 30%. Depending on the impact of these markets, the inventors have succeeded in reducing the amount of Co required for the alloys of the present invention so that the optimized alloy contains 0-6 atomic% of total Co. did. In particular, the alloy No. 1 shown in Table 1 was successfully used for a prismatic electric vehicle battery.

Without wishing to be bound by theory, in the alloys of the present invention,
Mn is thought to alter the microstructure so that the deposition of layers having hydrogen bond strengths outside the range of electrochemical utility is suppressed. One way Mn seems to achieve this is by increasing the mutual solubility of other elements in the main phase during solidification. In addition, Mn is an electrochemically active surface oxide that functions as a catalyst. It is believed that the multiple oxidation states of Mn catalyze the electrochemical discharge reaction by increasing the porosity, conductivity and surface area of the active oxide surface oxide film. This has led to a significant increase in storage capacity (see FIG. 4).

In addition to increasing porosity, Mn has enhanced low temperature performance,
It has other effects such as low battery pressure, and high cycle life. These effects are discussed in detail in US Pat. No. 5,277,999, which is incorporated by reference.

Mn can also act as a replacement for Fe. Not wanting to be bound by theory, but without Fe and Mn,
Mn promotes the main body dispersion of hydrogen at low temperatures,
And furthermore, it catalyzes the reaction between hydrogen and hydroxyl ions on the alloy surface, thereby assisting the electrochemical discharge reaction at low temperature. Due to the low temperature properties of such alloys, the catalytic properties of Mn seem to be emphasized in the absence of Fe or at least at very low concentrations.

Mn can also be used instead of Co. Without wishing to be bound by theory, it is believed that in the above alloys, Mn changes its microstructure and acts as a catalyst at the electrochemically active surface oxide portion.

The beneficial effects of Mn and Fe are also described in U.S. Pat.No. 5,096,667
No. 5,104,617, and U.S. Pat.
No. 56 describes it in detail. All of which are incorporated herein by reference.

It is widely believed in U.S. Pat. No. 5,104,617 that the incorporation of Fe in metal hydride hydrogen storage alloy materials adversely affects electrochemical properties. This idea was based on the knowledge that Fe was easily oxidized and corroded, especially in the presence of an alkaline electrolyte. Oxidation variously reduces the performance of metal hydride electrodes, and oxides of Fe were known in the prior art to have a negative effect on nickel hydroxide anodes, especially on charging efficiency, i.e. capacity and cycle life .

Many of the alloys of the present invention involve Mn. Mn to these alloys
The effect of the addition of is generally described in US Pat. No. 5,096,667. The addition of Mn usually results in improved charging efficiency. Without wishing to be bound by theory, it appears that this effect is derived from Mn's ability to improve the charging efficiency of the alloy to which it is added by oxidation resistance and oxygen recombination. It has been observed that the oxygen gas generated at the nickel hydroxide anode recombined on the surface of the metal hydride electrode.
Oxygen recombination is a particularly active oxidant in the environment, even when compared to alkaline electrodes.

The modifier elements of the base alloy of the present invention, especially Mn and Fe, and most particularly Co, alone or in combination with, for example, Mn / Al, act to catalyze the reduction of oxygen in metal hydride alloys. Oxidation of surrounding elements is avoided but can be reduced. It is believed that this function of the modified alloy provides a thinner, more stable surface, with reduced or even eliminated formation and accumulation of harmful surface oxides.

Without wishing to be bound by theory, it is believed that some additional factors explain the unexpected behavior of Mn and Fe in the base alloys of the present invention as follows: (1) Combination of Mn and excess Fe Affects the body alloy by affecting the grain boundaries or by affecting the equilibrium bond strength of hydrogen in the metal, thereby inhibiting the body diffusion rate of hydrogen in the metal through the formation of a composite phase structure. May have been given. In other words, the temperature dependence of the hydrogen bond strength may increase, thereby reducing the available voltage and the available capacity under cold discharge.

(2) It is believed that the combination of Mn and excess Fe increases the ductility of the alloy, thereby reducing the amount of surface area formation during the activation process, thereby resulting in lower electrode surface area for metallurgical reasons.

(3) It is believed that the combination of Mn and excess Fn in these alloys may inhibit low temperature discharge by altering the oxide layer itself with respect to conductivity, porosity, thickness, and / or catalytic activity. This oxide layer is an important factor in the discharge reaction and promotes the reaction of hydrogen from the base alloy of the present invention and hydroxyl ions from the electrode. We believe that this reaction is thin, conductive, porous,
It is believed that it is promoted by some catalytically active oxides.

The combination of Mn and excess Fe does not seem to be a problem under room temperature discharge, but showed a surprising tendency to slow the low temperature reaction. Complex oxide formation could result in slight changes in the oxide structure, such as pore size distribution or porosity. Since the discharge reaction produces inside the well oxide itself only in the metal hydride surface water, small pore size K ⁺ and OH to the oxide from the body of the electrolyte ^- might be causing ions slow dispersion . From room temperature discharge where the polarization is almost completely in the ohmic range to low temperature discharge where the activation and concentration polarization components are dominant, the physical structure of the oxide of Fe and Mn is compared to that of Mn alone. Could be substantially different.

Yet another possible explanation is that Mn and Fe have a multivalent oxidation state. Some elements in the oxide may actually change the oxidation state during the normal state of charge fluctuations as a function of the discharge rate, and be dependent on both temperature and processing,
It is believed that it may depend on the composition. These multi-oxidation states can have different catalytic activities affecting the porosity of the oxide as well as different densities.

A possible problem with composite oxides containing both Mn and excess Fe is that it slows the ability of Mn to change oxidation state when the Fe component is present in large amounts.

The function of Sn addition to the alloy consists of two elements. First, the addition of a small amount of Sn helps to activate the alloy used for the electrodes of the NiMh battery. Not wanting to be bound by theory,
This may be due to the desired corrosion during the initial heat treatment. The addition of Sn also has the desired function of cost reduction, since the alloy containing Sn can use inexpensive zirconium metal (such as Zircalloy).

Throughout the above discussion regarding oxides, it is noted that oxides may include other components of the base alloys of the present invention, such as V, Ti, Zr, Ni and / or Cr and other modifier elements. One of ordinary skill in the art should infer that the discussion of the complex oxide of Mn and Fe is merely for brevity, and that the actual function may involve different or complex descriptions involving such other elements.

Cathodes using the alloys of the present invention can be used in many types of hydrogen storage batteries and batteries. These cells include, for example, a substantially flat plate cathode, a separator, and a substantially flat, flat cell having an anode (i.e., counter electrode) operably aligned with the cathode; And a prismatic battery used in electric vehicles. The metal hydride battery of the present invention can use any suitable type of container, for example, made of metal or plastic.

A 30 weight percent aqueous potassium hydroxide solution is a preferred electrolyte.

In a particularly preferred embodiment, U.S. Pat.
Alloys used in combination with the advanced separator materials disclosed in No. 1 provide improved performance over the prior art for certain electrochemical applications.

In addition to the above improved technical performance, alloy modification is 30%
Provide cost benefits up to. One of the major factors affecting the cost of these alloys is the cost of vanadium metal. U.S. Patent No. 5,002,730, incorporated by reference
In this article, vanadium in the form of V-Ni or V-Fe offers significant cost advantages over pure vanadium. Such cost gains can be enhanced by using V-Fe in the base alloy of the present invention.

Example Preparation of Cathode Material The alloy materials described in Table 2 above and the comparative materials described in Table 3 were prepared as follows to prepare cathode materials. The specific alloys used are shown in the tables for each specific example. Alloy numbering is consistent throughout the specification and refers to Table 2 or Table 3.

The alloys in Tables 2 and 3 are from Fetcenko U.S. Pat. No. 5,002,73.
No. 4,948,423 to Fetcenko et al. By weighing the starting materials of the constituent elements and mixing them in a graphite crucible. The crucible and its contents were placed in a reduced pressure vacuum furnace and then pressurized with about 1 atmosphere of argon. The contents of the crucible are
It was dissolved by high frequency induction heating in an argon atmosphere. Melting was performed at a temperature of about 1500 ° C. to obtain a homogeneous melt. At this point, heating was stopped and the melt solidified under an inert blanket.

Next, the size of the ingot of the alloy metal was reduced by a multi-step process. The first step is “Hydride Reactor Apparatus for Hydrogen Comminu, which is specifically incorporated by reference.
tion of Metal Hydride Hydrogen Storage Alloy Mater
ial "by hydrogenation / dehydrogenation substantially as described in Fetcenko et al., US Pat. No. 4,983,756. This first step reduced the size of the alloy to less than 100 mesh. Next, the size of the material obtained from this hydrogenation / dehydrogenation process was further reduced using an impact milling process that accelerates the particles tangentially and radially to the impact block. The process is specifically incorporated by reference “Method for the Continuous Fabr
ication of Comminuted Hydrogen Storage Alloy Negat
U.S. Patent No. 4,915,8 entitled "ive Electrode Material"
No. 98.

A fraction of alloy metal having a particle size of less than 200 mesh and a mass average particle size of about 400 mesh (38 microns) is recovered from the impact milling process and a layer of alloy material is placed on a nickel screen current collector and the powder and They were coupled to the current collector by a process of compressing the current collector. Compression was performed under an inert atmosphere in two separate compression steps, each using a pressure of about 16 tons per square inch. After compression, the current collector and the powder deposited thereon were sintered in an atmosphere of about 2 atomic% hydrogen and the balance argon to form a cathode material. (Normally, sintering is not required for all applications. The need for sintering depends, of course, on the overall battery design and factors, such as charge balance.

These alloys and cathodes were activated using the alkaline etching process described in US Pat. No. 4,716,088, which is specifically incorporated by reference. As a practical matter, some oxidation occurs during the fabrication of the electrode, thus exposing the alloy powder or cathode of the present invention to an alkaline solution to "etch" or alter the nature of the surface oxides formed. And a variety of beneficial results. For example, etching changes the surface conditions of the alloy powder or formed cathode material such that improved charging efficiency is achieved even in the first charging cycle; promoting the ion dispersion required for the electrochemical discharge process It is believed that a gradient of the oxidation state is created at the surface of the material; and that the surface oxide is altered to achieve higher charge acceptability. Ogawa (Proceedings of the 1988 Power S
ources Symposium (Chapter 26, Metal Hydride Electro
de for High Energy Density Sealed Nickel−Metal Hy
A similar effect can be achieved by "etching" the alloy powder and then forming a cathode from this etched powder, as shown by Dride Battery. See also JPA 05/021 059 and JPA 05/013 077.

Battery Preparation The prepared cathode was combined with a nickel hydroxide anode to create a closed "C" electrode with a resealable vent using 30% KOH electrolyte, as described in US Patent No. 4,822,377.

Example 1 The completed batteries made as described above using the alloys shown in Table 3 were subjected to charging and discharging conditions to determine the energy density (mAh / g).

The data obtained from these tests is shown in Table 4 below.

Example 2 Corrosion measurements were performed using electrodes made from the alloys listed in Table 5. These electrodes were made by cutting thin slices (-1 mm thick) from an ingot of an alloy material. A copper wire for electrical measurement was attached to one side of the slice using silver epoxy cement. The electrode was placed on the epoxy resin such that only the surface to which the copper wire was attached was covered and the opposite surface of the electrode was exposed. The exposed surface was polished with a 0.3 micron aluminum oxide paste and its geometric area was measured for corrosion measurements.

The corrosion potential (E _corr ) and corrosion current (i _corr ) of these electrodes were measured using an EG & G PARC corrosion measurement device. This measurement was performed in a 30% KOH solution. The corrosion potential of each electrode was determined by measuring the open circuit potential against the Hg / HgO reference electrode for about 20 minutes after immersing the electrode in the solution. The corrosion current was measured using a polarization resistance (linear polarization) technique. This technique was performed by using a regulated scan of 0.1 mV / sec over the ± 20 mV range for E _corr . The resulting current was plotted linearly against potential. The slope of the potential current function E _corr is the polarization resistance (R _p ). Using R _p together with the Tafel constant β (assuming 0.1 V / mass change), the equation R _p = β _A β _c
/(2.3(i _corr ) (β _A + β _c )) was used to determine i _corr .

In view of the above, it will be apparent to those skilled in the art that the present invention identifies and encompasses a wide range of alloy compositions that, when introduced as a cathode in a metal hydride battery, result in a battery having improved performance characteristics. is there.

The drawings, discussion, and examples in this specification are merely illustrative of specific embodiments of the present invention, and are not intended to limit the implementation. It is the following claims and their equivalents that define the scope of the invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ovshinsky, Stamford Earl. United States 48013 Bloomfield Hills Scarre Road, Michigan 2700 (72) Inventor Chao, Benjamin S. United States 48083 Troy Sherwood Drive, Michigan 3513 (72) Inventor Reichmann, Benjamin United States 48323 West Bloomfield, McNicoll Trail, Michigan 3740 (56) References JP-A-7-73878 (JP, A) JP-A-6-88150 (JP, A) JP-A-4-137361 ( JP, A) JP-A-4-255669 (JP, A) JP-A-5-343059 (JP, A) JP-A 8-96804 (JP, A) JP-A 8-67936 (JP, A) JP Hei 5-347 156 (JP, A) JP-A-2-223150 (JP, A) JP-A-61-45563 (JP, A) JP-A-6-187983 (JP, A) JP-A-3-108273 (JP, A) JP-A-1-165737 (JP, A) JP-A-3-93158 (JP, A) JP-A-6-231763 (JP, A) JP-A-7-50163 (JP, A) JP-A-2-179798 (JP, A) JP-A-4-254503 (JP, A) JP-A-5-211063 (JP, A) JP-A-5-504376 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ H01M 4/38 H01M 4/24-4/26

Claims (13)

(57) [Claims] 1. An electrochemical hydrogen storage alloy having an oxide layer on the surface of a main body alloy, wherein the oxide layer has a nickel-rich region distributed over the oxide layer and having a diameter of 70 ° or less. Hydrogen storage alloy. 2. The method of claim 1 wherein the distance between said nickel-rich regions is between 2 and 300.
The electrochemical hydrogen storage alloy according to claim 1, which is Å. 3. The distance between said nickel-rich regions is 50-100.
The electrochemical hydrogen storage alloy according to claim 1, which is Å. 4. An electrochemical hydrogen storage alloy having an oxide layer on the surface of a main body alloy, wherein the oxide layer has a nickel-rich region distributed over the oxide layer and having a diameter of 70 ° or less, body alloy (base _{alloy) a Co b Mn c Fe d} Sn e ( here, the base alloy, 0.1-60 atomic percent Ti, 0.1 to 40
Atomic% Zr, 0-60 atomic% V, 0.1-57 atomic% Ni,
And 0 to 56 atomic% Cr; b is 0 to 7.5 atomic%; c is 1
3-17 atom%; d is 0-3.5 atom%; e is 0.2-1.0 atom%; and a + b + c + d + e = 100 atom%. ) Consisting of an electrochemical hydrogen storage alloy. 5. The electrochemical hydrogen storage alloy according to claim 4, wherein said oxide layer has a nickel-rich region with a diameter of 50-70 °. 6. The distance between said nickel-rich regions is between 2 and 300.
The electrochemical hydrogen storage alloy according to claim 5, which is Å. 7. The distance between said nickel-rich regions is 50-100.
The electrochemical hydrogen storage alloy according to claim 5, which is Å. 8. The method according to claim 8, wherein the oxide layer formed on the main body alloy has a thickness of 70.degree.
An electrochemical hydrogen storage alloy having a Ni-rich region of the following diameters: a first electrochemical hydrogen storage alloy; and a second alloy mechanically alloyed with respect to the first alloy; The two alloys are electrochemical hydrogen storage alloys that contain Ni-rich regions that remain after the components that are preferentially corroded during activation are eroded. 9. The method of claim 1, wherein the first electrochemical hydrogen storage alloy is TiVZrNi.
The electrochemical hydrogen storage alloy according to claim 8, which is classified as a system. 10. A second alloy, wherein _{ZrMn w V x M y Ni z} ( wherein, M is Fe or Co, w,
x, y and z are molar ratios of each element, where 0.4 ≦
w ≦ 0.8, 0.1 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.2, 1.0 ≦ z ≦ 1.5,
And 2.0 ≦ w + x + y + z ≦ 2.4. ); Either La or Ni component is higher than 0.1% and 25%
An alloy substantially corresponding to the formula LaNi ₅ which has a lower atomic ratio and is replaced by a metal M selected from groups Ia, II, III, IV and Va of elements other than the lanthanoid group of the periodic table ; formula TiV _2-x Ni _x (where a x = 0.2 to 0.6.) alloy having; formula _{Ti a Zr b Ni c Cr d} M x ( wherein, M is Al, Si, V, Mn, Fe,
Co, Cu, Nb, Ag or Pd, 0.1 ≦ a ≦ 1.4, 0.1 ≦
b ≦ 1.3, 0.25 ≦ c ≦ 1.95, 0.1 ≦ d ≦ 1.4, a + b + c
+ D = 3, and 0 ≦ x ≦ 0.2. An alloy having the formula ZrMo _d Ni _e, where d = 0.1-1.2 and e = 1.1-2.5
It is. At least one transition metal forming an alloy of 40-75% by weight selected from groups II, IV and V of the periodic table; and the electrochemical storage alloyed with at least one transition metal An alloy consisting of at least one additional metal constituting the balance of the alloy, wherein the additional metal is selected from the group consisting of Ni and Cr-Ni steels; and the main structure of the Mm-Ni system; a plurality of compound phases (here, the capacity of each compound phase is less than 10 [mu] m ³⁾ which are separated in the tissue electrochemical hydrogen storage alloy of claim 8, wherein is selected from the group consisting of an alloy consisting of. Wherein said first electrochemical hydrogen storage alloy (Base _{Alloy) a Co b Mn c Fe d} Sn e ( where base alloy 0.1 to 60 atomic% of Ti, 0.1 to 40 atomic% of Zr , 0-60 atomic% V, 0.1-57 atomic% Ni, and 0-56 atomic% Cr; b is 0-7.5 atomic%; c is 13
D is from 0 to 3.5 at%; e is from 0 to 1.5 at%; and a + b + c + d + e = 100 at%. The electrochemical hydrogen storage alloy according to claim 8, wherein 12. An electrochemical hydrogen storage alloy having an oxide layer on the surface of a main body alloy, said oxide layer being nickel-rich distributed over said oxide layer and having a distance between regions of 2 to 300 °. An electrochemical hydrogen storage alloy having an area. 13. The electrochemical hydrogen storage alloy according to claim 12, wherein said nickel-rich region has a nickel-rich region having a diameter of 70 ° or less.